FOREX · Beginner · 7 min read · 3 Nov 2026 · Navion Pro Research
Why Interest Rate Gaps Between Countries Move Currencies
If one bank paid you 4% on your savings and another paid 1%, you would know where to put your money. Currencies work in a similar way. This guide explains why the gap between two countries' interest rates is one of the biggest forces in forex.
Trading leveraged products carries a high level of risk to your capital. Losses can exceed deposits. Past performance is not an indicator of future results.
Key Points
- Money tends to move towards the currency that pays the higher interest rate, which can push that currency up.
- What moves a pair is the gap between the two rates, often called the interest rate differential.
- Markets look ahead. A change in where traders expect rates to go can move a pair before any rate actually changes.
- The rate gap also shapes the overnight swap on a forex position.
Why rates matter to currencies
A country's central bank sets its main interest rate. That rate affects what savers earn on deposits and what lenders earn on bonds in that currency.
When rates in one country are higher, banks, funds and companies around the world have a reason to hold that currency. To buy its bonds or deposits, they first have to buy the currency. That extra demand can lift its value.
The rate gap, or differential
A currency pair compares two currencies, so what matters is how their rates compare. Traders call this the interest rate differential.
| If | Then the pair often |
|---|---|
| The first currency's rate rises above the second's | Rises, as money moves towards the first currency |
| The gap between the two rates widens | Moves further in favour of the higher rate |
| The gap starts to narrow | Moves back in favour of the lower rate |
| Both central banks move by the same amount | Changes little, because the gap stays the same |
A pattern, not a rule.
Why expectations matter more than today's rates
Markets try to price in the future. If traders expect a central bank to raise rates in three months, the currency may rise now, long before the rate actually changes. When the rise finally happens, the price may barely move, because it was already expected.
This is why traders watch central bank speeches, meeting minutes and inflation figures so closely. Each one can shift expectations, and expectations move prices.
An example: a narrowing gap
This example is for illustration only.
Country A has an interest rate of 4.00%. Country B has a rate of 1.00%. The gap is 3 percentage points, and money has been flowing into Country A's currency.
- Country A's central bank then signals it may cut rates over the coming year.
- Country A's rate is still 4.00%, but traders now expect the gap to narrow.
- Some start selling Country A's currency ahead of the cuts, and the pair falls.
The rate did not change. The expected gap did, and that was enough to move the price.
Currencies often move on where rates are heading, not where they are today.
Rate gaps and your overnight swap
When you hold a forex position past the daily rollover at 17:00 ET, a swap is applied. The rollover stays at 17:00 New York time all year, because it follows US clocks through daylight saving changes.
The swap reflects the rate gap between the two currencies:
- If you buy the higher yielding currency, the swap may be smaller, and in some cases a credit.
- If you sell the higher yielding currency, the swap is usually a charge.
Swaps also include a financing charge, so a position can pay a swap in both directions. Swap rates change with market conditions, so check the current rate for each pair on the platform before you trade. On one day each week, the swap is tripled to cover the weekend. The day can vary, so check which day applies to each pair on the platform.
The carry trade, and its risks
Some traders buy a high yielding currency against a low yielding one and hold it, hoping to gain from the rate gap and from the higher yielding currency rising. This is called a carry trade.
It can work for long stretches when markets are calm. The risk is that it can unwind fast. When fear rises, traders often sell high yielding currencies and buy safer ones at the same time, and months of gains can disappear in days. A small move against a leveraged position can outweigh many nights of swap.
When central banks announce decisions
Rate decisions are some of the biggest events on the forex calendar. In US Eastern time:
- The US Federal Reserve announces decisions at 14:00 ET, eight times a year. That time stays the same all year, because it follows US clocks.
- The European Central Bank announces decisions at 08:15 ET for most of the year. In the few weeks each spring and autumn when US and European clocks change on different dates, it is 09:15 ET.
Check the economic calendar for the dates and times of every central bank meeting.
Risk disclosure: Trading involves significant risk of loss and is not suitable for all investors. Past performance is not indicative of future results. This brief is for information and education only. It is not investment advice, a recommendation or an instruction to buy or sell anything. The likely market reactions described here are our assessments of what could happen, not predictions, and markets can and often do move differently. Figures and forecasts come from third party sources and may change. Make your own decisions, and consider independent advice if you are unsure.
